Nearly half of the municipal research team at Bank of America Merrill Lynch, the biggest lead manager of municipal bond sales in the $3.7 trillion U.S. market, left the firm last week in a restructuring of the unit, the company confirmed on Monday.

Bank of America Merrill Lynch spokeswoman Selena Morris confirmed the departures of Page and Sitzer and said that Hallacy retired. Morris would not comment on whether the retirement of Hallacy, 57, was voluntary.

'A new structure will be announced shortly', Morris said. 'We remain committed to the municipal market'. The departures are not part of a workforce reduction, she said. She declined further comment.

In the meantime, The Wall Street Journal's MONEYBEAT column reports that Citigroup has bolstered its Australian ranks with the hire of former ANZ global head of fixed income Rob O’Callaghan, a person familiar with the matter said Monday.

O’Callaghan has joined the Wall Street bank as a managing director and senior portfolio manager within Citi’s Australian risk treasury business, which oversees management of the unit’s balance sheet.

Argentiere Capital AG, run by Gulati, 35, and a team of former colleagues from JPMorgan, started trading yesterday from its base in Zug, Switzerland, said the people, who asked not to be identified because the move hasn’t been made public. The fund will focus on volatility trades, betting on the rate at which stocks rise or fall.